Equal inches

In this lesson, students will begin measuring with nonstandard units and discover the need for a standard unit of measure. Students will also learn to measure to the nearest inch using an inch ruler correctly and record their results.

A lesson plan for grade 2 Mathematics

By Charlene Martin

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Related topics

• Learn more about hands-on, length, mathematics, and measurement.

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Learning outcomes

Students will:

• measure correctly using nonstandard units of measure.
• measure correctly using inches.
• record their results.
• share their results with the teacher and classmates or partner.

Teacher planning

Time required for lesson

1.15 hours

Materials/resources

• One copy of How Big is a Foot? written and illustrated by Rolf Myller
• 8 to 10 assorted color strips of paper of various lengths (to the nearest inch); will need one set per 2 to 4 children. Sets should be identical.
• Paper clips (small, regular, and jumbo sizes)
• Inch rulers
• Paper
• Pencils

Pre-activities

Students should have had experiences in linear measuring using nonstandard units and know how to lay nonstandard units end to end, without spaces between, in order to get an accurate measure.

Activities

1. Introduce activity by telling students that they will be using paper clips to measure the strips of paper in their bags. They will need to leave the paper clips on the strips so they can record their measures and others can observe their measures.
2. Partners lay their set of paper strips on their workspace and measure each using the paper clips you give them.
3. Partners record the color and length of each strip on their paper.
4. After partners are finished measuring, ask each group for their measure for a particular color paper and record on board or on chart paper. Immediately students will disagree as to the measure. Tell them that we will record all the measurements and later we can come back to figure out the problem. Next, suggest that we try another color and repeat the process.
5. After we find differing measurements for several of the different colored paper strips, instruct students to carefully walk around and look at what other groups have done. Students quickly see that the differing measurements are due to the size of the paper clips used.
6. Read How Big is a Foot? to students. Compare what happens in the book to what happened when we measured with paper clips.
7. Distribute rulers to students. Discuss leading edge if your rulers have this. Remind students to write “inch” after each measure.
8. Partners (or small groups) put away paper clips and use inch rulers to measure their set of paper strips. Again they record color and length of each.
9. After groups are finished measuring, compare measures for each color strip and note how much more accurate the information is when we all used the same standard unit. If measures do not match, this is an excellent time to have students work to find out why they do not match (usually due to the leading edge on ruler, or some students begin with the number 1 on ruler instead of the beginning edge).

Assessment

• Teacher observes and records students who are using ruler correctly; assists those using ruler incorrectly.
• Collect and review student recording sheets to see if student correctly records measurements as well as arrives at correct measurements.

Supplemental information

Comments

Be sure that the sets of colored paper strips are identical. This way you can use color as a reference and have everyone looking at the same piece. It also makes grading/reviewing student recording sheets easier when all blue measures should be the same, etc.

Keep the pace brisk at the beginning so students don’t have time to notice that the paper clips are different sizes. I give out sets of paper strips in plastic zip-top bags to partners or groups and instruct them to begin measuring as soon as they are given their paper clips.

It is also helpful if you place clips in identical boxes before passing them out. If the boxes look alike, they aren’t tipped off as to the size of the paper clips.

Early finishers can begin working on a Venn diagram (or double bubble map if you use Thinking Maps) to compare our paper clip measuring experience to the king’s experience in How Big is a Foot?